Levosimendan, which is the (-)-enantiomer of [[4-(1,4,5,6-tetrahydro-4-methyl-6-oxo-3-pyridazinyl)phenyl]hydrazono]prop anedinitrile (I), and the method for its preparation is described e.g. in EP 565546 B1. Levosimendan is potent in the treatment of heart failure and has significant calcium dependent binding to troponin. The use of levosimendan in the treatment of myocardial ischemia is described in WO 93/21921. Pharmacokinetics of levosimendan in man after i.v. and oral dosing is described in Sandell, E.-P. et al., J. Cardiovasc. Pharmacol., 26(Suppl.1), S57-S62, 1995. ##STR1##
It has now been found that therapeutically effective serum levels of levosimendan can be achieved by administering levosimendan transdermally. Transdermal delivery of levosimendan provides a safe method for administering levosimendan to a patient at a desired steady rate.